IEW #3: Sunset WaterWorks
Note: the given coordinates are for parking for a one-off approach.
See link below for IEW Series information including parking spots and map.
The cache was previously called simply Sunset Waterworks, but has now been incorporated as the 3rd cache in the IEW Series of 20 caches which takes you around some of the lovely countryside immediately to the east of Ilkley.
See GC8PCW2 Ilkley East Wander ~1: Intro and . . . Prick!? for information on the series and waypoints. See Gallery for an annotated map with cache locations and parking spots.
The cache, a small camo-taped plastic pot, is located near a fine sunset viewpoint (clouds permitting!) adjacent to a small hidden reservoir and associated waterworks above Wheatley Rakes, a lovely wooded area above Ben Rhydding and adjacent to the Golf Club.
I was unable to find any information on the reservoir but it presumably is fed by and stores water coming off Ilkley Moor for supply to lower areas. Presumably it is the same 'magic' water which was the basis of hydrotherapy for which Ilkley was renowned and for which the huge Ben Rhydding Hydro (see photo in Gallery) was established where the golf course now is - but that is another story (cache?) . . .
To find the cache:
If doing in IEW Series sequence: from IEW #2, continue following the trail heading south up and out of the woodland then along the edge of the golf course up to a grass-covered reservoir. Turn west here to locate the start of the multi.
If doing as a one-off: park at the Cow & Calf pub @ N 53 54.899 W 1 47.874 and then head back and down the road to N 53 54.926 W 1 47.920 the start of another public footpath. Follow this down to the cache location.
Alternative approach: park at or near N 53 55.157 W 1 48.206 which is the start of a public footpath on Constable Road. This passes by the location of GC79FEY Mighty Ulmus after which the path swings left at a Y-junction to join a small tar road which after a locked gate becomes a jeep track heading to the cache location.
Step 1: head for N 53 55.071 W 1 47.978 where you will find a waterworks access cover with the British Standard kite mark, the word Ductile and underneath this a BS 
number beginning EN 124 (the standard for Access Covers & Gully Gratings). The last figure of this = A
Step 2: now move a little up the track to N 53 55.071 W 1 47.975, the location of a Yorkshire Water sign. There is a warning on this advising the reader to avoid B things - all involving negative effects of gravity!
Step 3: onwards to the door giving access to the underground workings of the reservoir @ N 53 55.071 W 1 47.975. Keeping this securely locked is a large padlock with a 3-digit number on it, the sum of which = C
Note: 23/5/20 reported missing so use C=8
Step 4: at the same spot take one step backwards and look up to the left above the door, where you will see a ventilation block with D holes in it
Step 5: now scramble up the grassy slope on the south side of the structure to N 53 55.069 W 1 47.966 where there is another circular access cover, the names of the makers of which (both beginning with the letter S) are clearly indicated on it. The number of letters in the first name = E
The cache can be found at:
N 53 55.(B-3)E(A-5) W 1 47.(D-B)(A+1)C
